Vinokourov, who also captured a tough mountain stage in the Pyrenees, has maintained his innocence, saying that he has always raced clean and that he plans to fight the blood-doping charges.

"Never before this year's Tour de France have I ever been accused of violating any doping law," Vinokourov said in a statement. "I have been tested at least 100 times during my career. These test results simply make no sense. Given all the attention paid to doping offences, you would have to be crazy to do what I have been accused of, and I am not crazy."

According to the Union Cycliste Internationale's newly implemented anti-doping charter, Vinokourov could lose a year's salary and faces up to a two-year ban.

Vinokourov, considered a favourite to win the race, hypothesized that a crash in an early stage that damaged both his knees contributed to the positive result.

"I think it is a mistake, in part, due to my crash. I have spoken to the team doctors, who had a hypothesis that there was an enormous amount of blood in my thighs, which could have led to my positive test."

French biophysicist Michel Audran, a professor at Montpellier University, said it's easy to detect an illegal transfusion when the blood is tested for anomalies.

"If you are tested, the probability of not getting detected is feeble, one in 7,000," Audran said.

Blood transfusions increase the hemoglobin mass that carries oxygen to the muscles and, according to Audran, could increase a cyclist's performance by "three to 20 per cent."

In othercycling news, Spanish rider Iban Mayo tested positive for EPO during the final week of the Tour de France, his Saunier Duval team said Monday in a statement.

The team was informed of theresultsfrom a July 24 test conducted by cycling's governing body and "immediately suspended" Mayo, according to a statement posted on the team's website.